Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 3.4 09/27] vhost: fix total length when packets are too short | Date | Thu, 24 Apr 2014 14:55:43 -0700 |
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3.4-stable review patch. If anyone has any objections, please let me know.
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From: "Michael S. Tsirkin" <mst@redhat.com>
[ Upstream commit d8316f3991d207fe32881a9ac20241be8fa2bad0 ]
When mergeable buffers are disabled, and the incoming packet is too large for the rx buffer, get_rx_bufs returns success.
This was intentional in order for make recvmsg truncate the packet and then handle_rx would detect err != sock_len and drop it.
Unfortunately we pass the original sock_len to recvmsg - which means we use parts of iov not fully validated.
Fix this up by detecting this overrun and doing packet drop immediately.
CVE-2014-0077
Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- drivers/vhost/net.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
--- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -351,6 +351,12 @@ static int get_rx_bufs(struct vhost_virt *iovcount = seg; if (unlikely(log)) *log_num = nlogs; + + /* Detect overrun */ + if (unlikely(datalen > 0)) { + r = UIO_MAXIOV + 1; + goto err; + } return headcount; err: vhost_discard_vq_desc(vq, headcount); @@ -405,6 +411,14 @@ static void handle_rx(struct vhost_net * /* On error, stop handling until the next kick. */ if (unlikely(headcount < 0)) break; + /* On overrun, truncate and discard */ + if (unlikely(headcount > UIO_MAXIOV)) { + msg.msg_iovlen = 1; + err = sock->ops->recvmsg(NULL, sock, &msg, + 1, MSG_DONTWAIT | MSG_TRUNC); + pr_debug("Discarded rx packet: len %zd\n", sock_len); + continue; + } /* OK, now we need to know about added descriptors. */ if (!headcount) { if (unlikely(vhost_enable_notify(&net->dev, vq))) {
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